In late years, a content delivery service has been commercialized for delivering various digital contents, such as music, video, etc., and a content copyright management function has increased in importance for restricting playback times for the digital contents accumulated in home receivers, a transfer of the contents, a copy (or dubbing) of DVD-RAM, SD card, etc. to an external storage medium, from the point of view of a copyright protection and user's convenience.
If there is no restriction for copy times, the right for owner of copyright is not protected since an external storage medium storing the contents can be produced unrestrictedly. In contrast, there are needs to copy it to the external storage medium from the point of view of convenience when a user, who bought the contents, uses it in a car or outdoors within individual activity. Further, an inconvenience sometimes occurs such that the contents, which were bought, are all lost since a storage device in the receiver is broken down, therefore, a backup is insignificant.
For example, a music delivery system in which the copyright protection is executed in Patent literature 1 is configured by a server for executing a music content delivery, a charge settlement, etc., a user terminal for executing a procedure of purchasing the contents by accessing to the server from the user, an exclusive-use playback device for playing back purchased music, etc. The user accesses to the server from the user terminal via a network to purchase digital music data (AV contents) and a ticket capable of copying the music data plural times.
The music data and copy ticket is downloaded once to the user terminal from the server to further store the copy ticket in the exclusive-use playback device from the user terminal. The music data is also copied to the exclusive-use playback device. At this time, a number or numbers are subtracted from the number of copy ticket, and a copy history in the exclusive-use playback device is updated. The copy history of exclusive-use playback device is notified to the server when the exclusive-use playback device is coupled to the user terminal and the user terminal is also coupled to the server. In consequence of this configuration, it realizes that the copy can be executed and the system executes the copyright protection.
Patent Literature 2 discloses a content use system, in which a receiving terminal executes to purchase digital contents from a content delivery server to download, play back and export it, provides that a license appended to the digital contents is divided into a playback license and an export license to be managed as those, the playback license is can be duplicated in a predetermined range, and the export license is not allowed to duplicate it in the predetermined range, but allowed to move only, in consequence, a strict export control can be executed without recourse of export processing times.